Adult Contractures in Burn Injury: A Burn Model System National Database Study

Abstract

As the overall survival rate for burn injury has improved, increased emphasis is placed on postburn morbidity and the optimization of functional and cosmetic outcomes. One major cause of morbidity and functional deficits is that of joint contractures. The true incidence of postburn contractures and their associated risk factors remains unknown. This study examines the incidence and severity of contractures in a large, multicenter, burn population. The associated risk factors for the development of contractures are determined. Data from the National Institute on Disability and Rehabilitation Research Burn Model System database, for adult burn survivors from 1994 to 2003, were analyzed. Demographic and medical data were collected on each subject. The primary outcome measures included the presence of contractures, number of contractures per patient, and severity of contractures at each of nine locations (shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar spine, and thoracic spine) at time of hospital discharge. Regression analysis was performed to determine predictors of the presence, severity, and numbers of contractures, with P < .05 used for statistical significance. Of the 1865 study patients, 620 (33%) developed at least 1 contracture at hospital discharge. Among those with at least one contracture, the mean is three (3.38) contractures per person. The shoulder was the most frequently contracted joint (23.0%), followed by the elbow (19.9%), wrist (17.3%), ankle (13.6%), and knee (13.4%). Most contractures were mild (47.2%) or moderate (32.9%) in severity. Statistically significant predictors of contracture development were male sex, black race, Hispanic ethnicity, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the severity of contracture included male sex, black race, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the number of contractures included male sex, medical problems, flash burn, neuropathy, TBSA burned, and TBSA grafted. Similar to a previous single-center study on postburn contractures, approximately one third of the patients with an eligible burn injury requiring autografting developed a contracture at hospital discharge. It is likely that these contractures develop despite early therapeutic interventions such as positioning and splinting; therefore, the challenge to the burn community remains, to identify new and better prevention strategies.

Contractures represent a major source of morbidity for patients recovering from burn injury. Postburn contractures often have a devastating impact on the quality of life and one’s ability to perform activities of daily living.¹ Although prevention remains the most rational approach, a significant percentage of burn survivors will develop functionally limiting, postburn contractures even at the best burn centers and despite aggressive, early physical and occupational therapy. Surgical correction with skin grating, adjacent tissue rearrangement, or local and distant flaps is typically required, yet carries a significant rate of recurrence with often undesirable cosmetic outcomes. Furthermore, postburn contractures and the need for surgical treatment, which often require additional postoperative physical and occupational therapy, increase the financial burden of burn care and limit patients from returning to work.

Contractures are defined as an inability to perform full range of motion (ROM) of a joint.² Burns damage the skin and often the underlying soft tissue, muscle, and bone; therefore, burn-injured patients are at risk for developing joint contractures. Postburn contractures ultimately result from a combination of wound contracture, primarily caused by fibroblasts and a natural physiological response to wound healing, as well as from scar contracture, primarily caused by myofibroblasts.³ Some measure of burn scar contracture is expected and may be considered within normal range; however, excessive contracture of scar, such as hypertrophic scarring (HTS), is considered pathological. Patients who develop contractures face the possibility of additional medical problems, including functional deficits, and interference with wound and graft healing. Functionally, contractures can inhibit normal ambulation and transfers, fine motor tasks, and activities of daily living such as eating, bathing, and grooming.^4–8

A combination of factors likely contribute to postburn contracture formation: 1) injury-related factors include the depth, extent, cause, and location of burn; 2) patient-related factors include genetic, race, skin color, age, sex, nutritional status, and compliance with therapy; and 3) treatment-related factors including the type and timing of wound closure, the wound bed, and prevention strategies utilized.^3,9–12 The cellular and biological basis of wound, scar, and skin graft contracture, as well as HTS, has been extensively researched and well described.^13,14 Furthermore, a prolonged stay in an intensive care unit (ICU), even in the absence of a burn injury, has been shown to be associated with a 34% incidence of functionally limiting joint contracture.¹⁵

One of the first and largest publications demonstrating the epidemiology of burn contractures was a retrospective review of 681 patients performed by Dobbs and Curreri in 1972. They found a 28% incidence of contractures, with the hand, elbow, and shoulder being the most frequently involved joints. TBSA and burn depth were noted to be associated with contracture development.¹⁶ The first review of prospectively collected data on burn contractures was performed in 2006 by Schneider et al in which they reviewed single-center data of 985 burn patients. The shoulder (38%) was identified as the most frequently contracted joint, followed by the elbow (34%) and knee (22%). Of the study population, 39% demonstrated at least one contracture with a mean of three contractures per person. Most contractures were noted to be mild (60%) or moderate (32%). Statistically significant predictors of contracture development were length of stay, TBSA grafted, and TBSA burned.¹⁷ Predictors of contracture severity included graft size, amputation, and inhalation injury. Limitations of the study were that it only examined four joints (shoulder, elbow, hip, and knee) and included data from only one burn center. Herein, we build on Schneider et al’s review by examining nine major joints in a larger patient population and from five major burn centers. Furthermore, this is the first and largest study on postburn contractures to examine prospectively collected data from a national, multicenter, burn outcomes database. We examine the incidence and severity of contractures and determine the associated risk factors for their development.

METHODS

Prospectively collected data from the National Institute on Disability and Rehabilitation Research (NIDRR) Burn Model System (BMS) database, for adult burn survivors from 1994 to 2003, were analyzed. The NIDRR BMS database comprises patients who meet at least one of the following current inclusion criteria:

1. Burn injury greater than or equal to 10% TBSA, which required surgery for at least some portion of wound closure (defined as autografting); age: 65 years and older.

2. Burn injury greater than or equal to 20% TBSA, which required surgery for at least some portion of wound closure; age: 0 to 64 years.

3. Electrical high voltage/lightning injury, which required surgery for at least some portion of wound closure.

4. Burn injury of any size to critical area(s): face and/or hands and/or feet and/or genitals, which required surgery for at least some portion of wound closure.

During the 10 years of this study, and the 20 years of the NIDRR BMS database, minor modifications have been made to the inclusion/exclusion criteria. These modifications can be found at http://burndata.washington.edu/standard-operating-procedures, and the complete detailed inclusion and exclusion criteria have been previously described.¹⁸ Primary outcome measures included the presence, severity, and number of contractures. Demographic (age, sex, and ethnicity [white, black, Hispanic, and other]) and medical data were collected. If demographic data cannot be collected through patient report, they are collected from the medical record. Medical data included length of hospital stay, length of ICU stay, presence of concomitant medical problems (defined as medical problems that might alter the course of recovery from the burn, such as diabetes, chronic obstructive pulmonary disease, heart disease, asthma), cause of burn, inhalation injury, neuropathy, heterotopic ossification, amputation as the result of the burn injury, and TBSA burned and grafted (recorded as a whole number percentile). Neuropathy required determination by a physician and included upper or lower extremity sensory and/or motor abnormalities or generalized peripheral neuropathy. We chose to report on all contractures recorded in the NIDRR database, except for that of the hand. This included musculoskeletal contractures (eg, joint) and nonjoint contractures. These areas of interest included the shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar spine, and thoracic spine. Lumbar and thoracic data were only collected after 1998. At the time of discharge from the hospital, specified areas were examined for a total of 15 studied sites per subject (neck, lumbar, and thoracic were unilateral). The subjects’ active ROM at each joint was measured using a goniometer and inclinometer with a standardized technique.¹⁹ Multiple planes of motion (ie, flexion/extension) were investigated at each joint. The specific methodology for ROM measurements at each joint is detailed in the Model System for Burn Injury Rehabilitation National Database Data Dictionary.²⁰ Joint muscle action in each plane is assigned a normal ROM based on physical examination conventions.^19,21 As in a similar study by Schneider et al,¹⁷ each impaired joint muscle action is assigned a severity rating. Such ratings are determined by dividing the normal ROM value equally in thirds (mild, moderate, and severe; Table 1). For the purposes of this analysis, a limitation in the ROM in at least one plane of motion at a specified joint was considered to be a contracture at that joint. Furthermore, if more than one muscle action was limited at a joint, the severity of the most impaired muscle action at that joint was considered to represent the severity of contracture at that joint. Data were also collected for the presence of ectropion, microstomia, and nasolabial contractures. These contractures contributed to analyses of frequency and number, but not to severity, of contracture.

Table 1.

Range of motion severity ratings by joint muscle action (degrees)

Joint	Muscle Action	Contracture Severity
		Mild	Moderate	Severe	Expected19,21
Shoulder	Flexion	120 to 180	60 to 119	<60	180
	Extension	32 to 50	16 to 31	<16	50
	Abduction	120 to 180	60 to 119	<60	180
	Adduction	32 to 50	16 to 31	<16	50
Hip	Flexion	67 to 100	34 to 66	<34	100
	Extension	20 to 30	10 to 19	<10	30
	Abduction	26 to 40	13 to 25	<13	40
	Adduction	13 to 20	7 to 12	<7	20
Elbow	Flexion	93 to 140	46 to 92	<46	140
	Extension	140 to 93	−46 to 92	>−46	0
	Pronation	53 to 80	26 to 52	<26	80
	Supination	53 to 80	34 to 66	<26	80
Knee	Flexion	100 to 150	50 to 99	<50	150
	Extension	−150 to 100	−99 to 50	>−50	0
Wrist	Flexion	40 to 59	20 to 39	<20	60
	Extension	40 to 59	20 to 39	<20	60
	Radial DV	13 to 19	6 to 12	<6	20
	Ulnar DV	20 to 29	10 to 19	<10	30
Ankle	Dorsiflexion	13 to 19	6 to 12	<6	20
	Plantarflexion	26 to 39	13 to 25	<13	40
	Inversion	20 to 29	10 to 19	<10	30
Neck	Extension	50 to 74	25 to 49	<25	75
	Rotation (L and R)	53 to 80	26 to 52	<26	80
	Lateral flexion (L and R)	30 to 44	15 to 29	<15	45
Lumbar	Forward flexion	53 to 79	26 to 52	<26	60
	Extension	40 to 59	20 to 39	<20	0
	Lateral flexion	16 to 24	8 to 15	<8	25
Thoracic	Forward flexion	16 to 24	8 to 15	<8	60
	Rotation (L and R)	20 to 29	10 to 19	<10	30

DV, deviation; L, left; R, right.

Statistical Analysis

The frequency and severity of contractures at each joint, and number of contractures per patient at hospital discharge, were calculated. Logistic regression analysis was used to determine predictors of the presence of contractures. Ordered logistic regression was used to determine the severity of contractures. Negative binomial regression, one form of a multivariate analysis, was used to determine predictors of the number of contractures. Negative binomial regression was used because the variance assumption underlying Poisson regression was violated. The negative binomial regression model adjusts for this overdispersion. The potential predictors were the demographic and medical data (as detailed previously). Violations of statistical assumptions and goodness-of-fit test were analyzed. A P < .05 was used for statistical significance. In addition, the level of multicollinearity was evaluated via examination of condition numbers and variance decomposition proportions and determined to be non-significant. Further details with respect to the statistical logic of model building for this analysis can be found in Appendix 1, Supplemental Digital Content 1, at http://links.lww.com/BCR/A44.

RESULTS

The demographic and medical data of the study population are presented in Table 2. One thousand eight hundred sixty-five adult patients were included in the analysis. Average age was 41.7 years, and average TBSA was 18.3%. The frequency and severity of limitations by joint muscle action is presented in Table 3. Shoulder flexion (n = 438) and abduction (n = 272), knee flexion (n = 275), and elbow flexion (n = 275) and extension (n = 299) were the most frequent joint muscle action limitations. Using the methodology described previously, contracture frequency and severity at each joint was tabulated and is presented in Table 4. The shoulder (23.0%) was the most frequently contracted joint, followed by the elbow (19.9%), wrist (17.3%), ankle (13.6%), and knee (13.4%). Most contractures were mild (47.2%) or moderate (32.9%) in severity. Among the study population, 620 patients (33%) demonstrated at least 1 contracture at hospital discharge. In total, 2097 joints were contracted resulting in an average of 3 (3.38) contractures per person (among those with at least 1 contracture). The frequency of contractures is presented in Table 5. The frequency of microstomia (0.27%), ectropion (0.86%), and nasolabial contractures (0.16%) were also determined. A multivariate regression analysis was used to identify predictors of postburn contracture development (Table 6), contracture severity (Table 7), and number of contractures (Table 8). Statistically significant predictors of contracture development include male sex, black race, Hispanic ethnicity, medical problems, neuropathy, TBSA grafted, and TBSA burned, whereas female sex was a protective factor. Predictors of the severity of contracture include male sex, black race, medical problems, neuropathy, TBSA grafted, and TBSA burned, and female sex was a protective factor. Predictors for the number of contractures include male sex, medical problems, flash burn, neuropathy, TBSA grafted, and TBSA burned, and again female sex was a protective factor. There were no violations of statistical assumptions or goodness-of-fit test for these analyses.

Table 2.

Demographic and medical characteristics of the study population

Total number of study patients	1865
Male (%)	77.5
Age at injury (yr), mean (SD)	41.7 (15.5)
Ethnicity (%)
Caucasian	69.0
Black	15.0
Hispanic	10.0
Other	5.4
Length of stay (d), mean (SD)	25.0 (24.0)
Inhalation injury (%)	10.2
Percent TBSA burned, mean (SD)	18.3 (16.3)
Causative factor (%)
Fire/flame	59.5
Electrical	7.2
Flash	5.3
Scald	9.3
Grease	7.1
Other	11.3

Table 3.

Severity and frequency of range of motion limitation by joint muscle action (degrees)

Joint	Muscle Action	Severity
		Mild	Moderate	Severe	Total
Shoulder (%)	Flexion	248 (57)	168 (38)	22 (5)	438
	Extension	15 (27)	10 (18)	31 (55)	56
	Abduction	132 (49)	127 (47)	13 (5)	272
	Adduction	3 (8)	2 (5)	32 (86)	37
Hip (%)	Flexion	63 (68)	26 (28)	4 (4)	93
	Extension	10 (18)	16 (28)	31 (54)	57
	Abduction	20 (40)	27(54)	3 (6)	50
	Adduction	3 (11)	9 (33)	15 (56)	27
Elbow (%)	Flexion	205 (75)	57(21)	13 (5)	275
	Extension	270 (90)	29 (10)	0 (0)	299
	Pronation	44 (61)	13 (18)	15 (21)	72
	Supination	92(54)	46 (27)	33 (19)	171
Knee(%)	Flexion	156 (57)	104(38)	15 (5)	275
	Extension	108 (98)	0 (0)	2 (2)	110
Wrist (%)	Flexion	69(59)	39 (34)	8 (7)	116
	Extension	82 (62)	39 (30)	11 (8)	132
	Radial deviation	15 (58)	6 (23)	5 (19)	26
	Ulnar deviation	21 (54)	16 (41)	2 (5)	39
Ankle (%)	Dorsiflexion	34 (17)	56 (28)	111 (55)	201
	Plantarflexion	48 (31)	24 (15)	83 (54)	155
	Inversion	7 (21)	17 (52)	9 (27)	33
	Eversion	7 (21)	19 (58)	7 (21)	33
Neck (%)	Forward flexion	85 (89)	7 (7)	3 (3)	95
	Right rotation	8 (32)	13 (52)	4 (16)	25
	Left rotation	9 (36)	16(64)	0 (0)	25
	Extension	5 (13)	21 (55)	12(32)	38
	Right lateral flexion	21 (68)	6 (19)	4 (13)	31
	Left lateral flexion	19 (61)	7 (23)	5 (16)	31
Lumbar (%)	Forward flexion	1 (100)	0 (0)	0 (0)	1
	Right lateral flexion	1 (50)	1 (50)	0 (0)	2
	Left lateral flexion	2 (67)	1 (33)	0 (0)	3
Thoracic (%)	Forward flexion	6 (75)	1 (13)	1 (13)	8
	Right rotation	0 (0)	0 (0)	0 (0)	0
	Left rotation	0 (0)	0 (0)	0 (0)	0
Total (%)		1809 (56)	923(29)	494 (15)	3226

Table 4.

Contracture severity and frequency by joint (degrees)

Joint	Contracture Severity
	Mild	Moderate	Severe	Total (%)
Shoulder	231	190	61	482 (23.0)
Elbow	263	106	47	416 (19.9)
Hip	49	42	43	134 (6.4)
Knee	160	104	17	281 (13.4)
Ankle	29	72	185	286 (13.6)
Wrist	171	146	45	362 (17.3)
Neck	78	27	19	124 (5.9)
Lumbar	3	1	0	4 (0.2)
Thoracic	6	1	1	8 (0.4)
Total (%)	988 (47.2)	687 (32.9)	419 (19.9)	2097

Each impaired joint muscle action is assigned a severity rating determined by dividing the normal range of motion value equally in thirds (mild, moderate, and severe).

Table 5.

Contracture frequency (N = 1865)

Patients with at least one contracture (%)	620 (33.2)
Total number of contractures	2097
Mean number of contractures per person if at least one	3.38
Patients with only one contracture (%)	141 (7.6)
Patients with two contractures (%)	147 (7.9)
Patients with three contractures (%)	91 (4.9)
Patients with four contractures (%)	92 (4.9)
Patients with more than four contractures (%)	149 (8.0)

Table 6.

Logistic regression analysis of predictors of the presence of contractures

Variable	Odds Ratio	SE	t	P > |t|	95% Confidence Interval
Female	0.784	0.061	−3.15	.002	0.674 to 0.912
Black	2.172	0.812	2.08	.038	1.045 to 4.518
Hispanic	1.461	0.247	2.24	.025	1.049 to 2.034
Other ethnicity (not white, black, or Hispanic)	0.820	0.221	−0.74	.460	0.484 to 1.389
Medical problems	1.377	0.145	3.04	.002	1.121 to 1.692
Neuropathy	1.697	0.201	4.46	<.001	1.345 to 2.141
TBSA burned	1.060	0.015	4.14	<.001	1.032 to 1.091
TBSA grafted	1.067	0.015	4.67	<.001	1.038 to 1.097

Table 7.

Ordered logistic analysis of predictors of the severity of contractures

Variable	Odds Ratio	SE	t	P > |t|	95% Confidence Interval
Female	0.769	0.762	−2.65	.008	0.633 to 0.934
Black	2.179	0.698	2.43	.015	1.163 to 4.083
Hispanic	1.288	0.175	1.86	.063	0.986 to 1.683
Other ethnicity (not white, black, or Hispanic)	0.823	0.190	−0.84	.401	0.523 to 1.296
Medical problems	1.356	0.674	6.14	<.001	1.230 to 1.495
Neuropathy	1.584	0.133	5.47	<.001	1.343 to 1.868
TBSA burned	1.075	0.140	5.51	<.001	1.047 to 1.102
TBSA grafted	1.036	0.008	4.87	<.001	1.022 to 1.051

Table 8.

Negative binomial regression of predictors of the number of contractures

Variable	IRR	SE	t	P > |t|	95% Confidence Interval
Female	0.773	0.041	−4.87	<.001	0.697 to 0.857
Length of hospital stay	1.008	0.007	1.05	.293	0.993 to 1.022
Presence of medical problems	1.281	0.070	4.52	<.001	1.151 to 1.427
Electricity	1.303	0.261	1.32	.186	0.880 to 1.928
Flash	1.128	0.043	3.18	.001	1.047 to 1.215
Scald	1.264	0.433	0.68	.494	0.646 to 2.472
Grease	1.221	0.128	1.90	.057	0.994 to 1.500
Other ethnicity (not white, black, or Hispanic)	0.908	0.052	−1.70	.089	0.813 to 1.015
Neuropathy	1.284	0.136	2.36	.018	1.044 to 1.580
TBSA burned	1.049	0.013	3.93	<.001	1.024 to 1.075
TBSA grafted	1.073	0.008	9.38	<.001	1.057 to 1.089

DISCUSSION

This work represents one of the largest published review of burn contractures and the first to utilize the NIDRR BMS national burn outcomes database. We confirm previous studies indicating that postburn contractures remain a common morbidity after major burn injury. Burn centers contributing to the NIDRR BMS database are large, regional, U.S. burn centers verified by the American Burn Association (ABA) with early interventions of aggressive occupational and physical therapy. Yet despite this fact, 33% of patients in this review developed at least one contracture.

There are a multitude of reasons for this relatively high incidence of contracture. Regional burn centers often treat the most seriously injured, those with the most critical injuries, larger TBSA burned, and grafted, and are therefore at a statistically higher risk of developing contractures. In fact, inclusion in the NIDRR BMS database necessitates a relatively extensive injury that requires skin grafting. Larger burns are also more likely to cross multiple joints and require multiple surgical interventions, which in turn require a period of postoperative immobilization for appropriate healing; all of which has been associated with contracture development. A large burn injury typically requires an extended length of ICU stay, which, alone, is associated with a significant incidence of contracture.¹⁵ Clavet et al examined all patients admitted to an academic hospital ICU for more than 2 weeks (nonburn injured patients) and found a 39% incidence of contracture, of which 34% were functionally limiting. Although there are methodological differences between Clavet et al’s study and the current study with respect to the number of locations examined (10 vs 15) as well as the definitions of contracture and functional limitations, the results are similar. Therefore, the influence of a prolonged ICU stay (>14 days) alone is likely to contribute significantly to the development of contractures in our patient population. Interestingly, in our study, severe ankle contractures were notable more common than mild and moderate contractures. Further analysis demonstrated that patients with ankle contractures are more likely to have had an ICU stay (P < .001). Furthermore, considering that the average length of ICU stay in this study, for those patients who spent at least 1 day in the ICU, was 17.1 (SD, 20.8), our incidence of ankle contractures actually appears relatively low. Finally, it is always important to consider that the overall incidence of contracture will be directly related to the number of joints/locations examined.

Similar to Schneider et al’s 2006 single-center study, the majority of contractures were mild (47.2%) or moderate (32.9%); however, the incidence of severe contractures in the current review is more than twice than previously noted (20 vs 8%). This may in part be because of the inclusion of the ankle, in the current study, which had the highest incidence of severe contractures (65% of ankle contractures were severe). Also similar to the study by Schneider et al was the fact that the shoulder and elbow remained the two most commonly involved joints with shoulder flexion and abduction the most common muscle actions for limited ROM. However, the inclusion of wrist, ankle, and knee, in the current study, were all more commonly involved than that of the hip.

Given the relatively high incidence of postburn contractures, it seems reasonable to ask whether our current prevention strategies are effective. The frequency of contractures in the current study (33%) is similar to that found in the review by Dobbs and Curreri (28%), more than 40 years before, similar to that of Schneider et al’s study (39%) and even similar to Clavet et al’s study (39%) of non-burn patients with prolonged ICU stay. It should be noted that direct comparison between these studies, as well as other published studies on contracture rates, is not valid given differences in the study populations, number of joints examined, and definitions of contracture and functional deficit. However, similar contracture rates in this study compared with historical studies may yield two indications. First, the similar contracture rates may be because of less mortality due to improved medical and surgical management. Because more patients are surviving larger burns, greater possible morbidity is a result. Thus, a relatively stable contracture rate (33% vs Dobbs and Curreri’s 28%) could actually indicate improvements in prevention techniques, given that survival of major burns is more likely. In addition, when a 33% rate of contracture in this current study is compared with more recent studies, such as Schneider et al’s 39% finding that evaluated a fewer number of joints, improvement in contracture prevention could again be a possibility given that more areas were included in this study and a less or stable rate is noted. Second, current prevention strategies are mostly composed of static splinting and active/passive ROM exercises. The role of static splinting and the specifics of technique, however, remain controversial.²² Very few high-quality trials on splinting for prevention of burn contractures are available. The only randomized controlled trial on splinting of adult burns, written by Kolmus et al,²³ failed to show a benefit of static axillary splinting for axillary burns. Adherence to splinting was low, 77% at week 1 and 16% at week 12, as the majority of noncompliant patients reported that their arm was moving normally. In fact both groups showed significant improvements in shoulder ROM, and the additional benefit of splinting was not evident, suggesting that the tailored exercise regimen utilized in the study was mostly responsible for such improvements.

The findings of the study by Kolmus et al correspond to a review of the literature on static splinting for burns, by Schouten et al, in which no strong supporting evidence was identified, and we are reminded of the pathophysiology of scarring/contracture, ie, that mechanical tension is a strong stimulus for hypertrophic and abnormal scar formation. Static splinting results in scar tension. Tensile forces have been shown to induce transdifferentiation of fibroblasts into myofibroblasts and to down-regulate fibroblast proapoptotic genes, favoring the abnormal collagen deposition seen in HTS.^13,14 For patients with burn-associated joint contractures, Godleski et al²⁴ demonstrate significant improvements in ROM, with an intensive stretching protocol, in the absence of splinting. However, this study had a patient population of only nine. Prolonged durations of mechanical stretching have also been shown effective in contracture reduction as described in the systematic review by Furia et al.²⁵

Despite the fact that our knowledge of specific evidence-based strategies for contracture prevention are still limited, the identification of high-risk patients is still a clinically useful endeavor. In this study, multivariate analyses were performed to determine predictive factors associated with the presence, severity, and number of contractures postburn injury. Statistically significant predictors included male sex, the presence of medical problems, neuropathy, TBSA grafted, and TBSA burned. Therefore, male patients with concomitant medical issues and more extensive, deeper burns are most at risk for developing more contractures and contractures of worse severity. These findings are consistent with Schneider et al’s 2006 study of burn contractures, in which TBSA grafted was also found to be a predictor of presence, severity, and number of contractures. Schneider et al’s publication found other factors, typically associated with severe burn injury, to be significant predictors as well, such as inhalation injury, length of stay, and amputation. The current study, however, did not corroborate these specific predictors. Nevertheless by identifying such factors, health care professionals, and researchers can best target prevention strategies in our search for the most effective approach.

There are a number of limitations of this study. First, these data were collected from 1994 to 2003. To the extent that burn care has changed over this time period, the results of this study may not accurately reflect current burn practice. As stated previously, the criteria for inclusion into the NIDRR BMS database select those with more severe burns and, therefore, may not be representative of all burn patients and burn centers. In addition, and in concurrence with a previous trial, we chose to evaluate the rate of contracture at one time point—hospital discharge. Postburn contractures may improve, or worsen, over time depending on a number of factors including therapy, patient compliance, and development of HTS and tension forces across a joint. In addition, the presence of various confounding factors at the time of discharge, such as pain, weakness, and influence of medication, may have influenced ROM measurements. Therefore, it is possible that the contracture rates reported here do not necessary represent the rate of postburn contracture found over time.

We did not explore measures of quality of life or functional outcome. Future research may examine the effect of contracture severity on quality of life and function, as well as the correlation between contractures and return to work outcomes. Furthermore, details of physical and occupational therapy sessions, splinting techniques, time to full active ROM, time of immobilization, and time to complete wound closure were not recorded in the NIDRR database and are all valuable data points for future analyses. All study centers were ABA-verified burn centers and, as such, have physical and occupational therapy services in place as required for this verification.²⁶ Details on scar management techniques were also not available, but should be included in future studies, as should other potential risk factors for HTS, such as race.^27,28 Furthermore, determining the cumulative effects of multiple contractures on limb function is a future direction for further analysis. Finally, Richard et al²⁹ has expanded our understanding of burn location as it relates to contracture formation using the concept of cutaneous functional units. For example, burns of the abdomen can contribute to contractures at the shoulder as a result of skin recruitment and the availability of skin in certain areas of the body. The extent to which one can attribute burns of different anatomical locations to contracture development at specific locations, however, is an underdeveloped concept that deserves further investigation. Future investigations of postburn contracture may benefit from the utilization of this concept of cutaneous functional units.

CONCLUSION

Approximately one third of burn patients admitted to one of the BMS ABA-verified burn centers with a severe burn injury exhibited a contracture at discharge despite aggressive physical and occupational therapeutic interventions. Similar to previous findings, risk factors for the development of postburn contractures include male sex, the presence of medical problems, neuropathy, TBSA grafted, and TBSA burned.